The objectives of this research are to utilize measurements related to dopaminergic neuronal transmission in order to elucidate the actions of neuroleptic and psychotogenic drugs and to assist in classification and treatment assessment in the non-organic psychotic disorder. These studies are directed toward an understanding of schizophrenia and related psychotic disorders. The following specific projects are proposed 2) an assessment of a neuroleptic (haloperidol) and a benzodiazepine (diazepam) alone and in combination upon regional brain dopamine (DA) metabolism in the rat 2) measurement of regional changes in brain DA metabolism produced by psychotogenic drugs and an exploration of pharmacological approaches for reversing these changes 3) use of plasma catecholamine metabolites as markers for a subgroup of patients with psychotic disorders who may have unique clinical characteristics. Methods to be employed include acute and chronic drug administration to rats and measurement of regional brain homovanillic acid (HVA), dopamine (DA), methoxyhydroxyphenothylglycol (MHPG), and norepinephrine (NE). Clinical studies will involve measurements of catecholamine metabolites in plasma in conjunction with a variety of clinical variables in psychotic inpatients.